DIfferent forms of IGF-binding proteins have been identified in human plasma, a low molecular weight form and a high molecular weight form. The low molecular weight IGF-binding protein (IGFBP1) is synthesized in liver, secretory endometrium, and decidua. It binds both IGF I and IGF II with high affinity.
NCBI Summary:
This gene is a member of the insulin-like growth factor binding protein (IGFBP) family and encodes a protein with an IGFBP domain and a thyroglobulin type-I domain. The protein binds both insulin-like growth factors (IGFs) I and II and circulates in the plasma. Binding of this protein prolongs the half-life of the IGFs and alters their interaction with cell surface receptors. [provided by RefSeq, Jul 2008]
General function
Extracellular binding protein
Comment
Association of In Vitro Fertilization Outcome with Circulating Insulin-like Growth Factor Components Prior to Cycle Initiation. Ramer I et al. (2015) Components of the insulin-like growth factor (IGF) system enhance in vitro embryo quality and implantation rates in both animal models and in human IVF. We evaluated whether differences in serum levels of these components in women prior to initiation of an IVF cycle would be predictive of subsequent outcome. In this retrospective study sera from women obtained at day 2 of their IVF cycle (at baseline before stimulation) were assayed for IGF-I, IGF-II and IGF binding protein (BP)-1 by ELISA. Samples from 54 women with a live birth, 38 with a transient biochemical pregnancy, 45 with a spontaneous abortion, 54 who did not become pregnant and 35 who had an ectopic pregnancy were available for analysis. Associations between the assays and outcome were evaluated by the Kruskall Wallis test and ROC analysis. There were no differences in the number of oocytes retrieved, oocyte quality, fertilization rates, or embryo grade between groups. Median concentrations of IGF-I were elevated in women with a live birth (29.1 ng/ml) as compared to women with a biochemical pregnancy (25.6 ng/ml), spontaneous abortion (21.2 ng/ml), who were not pregnant (18.7 pg/ml) or who had an ectopic pregnancy (4.2 pg/ml) (p <0.001). Conversely, median levels of IGF-II were reduced in women with a live birth (294.5 ng/ml) as opposed to 357.5, 393.6, 407.2 and 426.9ng/ml in women with a biochemical pregnancy, ectopic pregnancy, spontaneous abortion or not pregnant, respectively (p<0.001). Median IGFBP-1 concentrations were markedly elevated in women with a live birth (23.6 ng/ml) compared to 18.3, 14.1, 13.8 and 9.5 ng/ml in women with a biochemical pregnancy, spontaneous abortion, not pregnant or with an ectopic pregnancy (p<0.001). The combination of IGF-I and IGFBP-1 best predicted the occurrence of a live birth with an area under the curve of 0.892. Maternal serum levels of IGF-I, IGF-II and IGFBP-1 prior to initiation of an IVF cycle are correlated with the likelihood of a live birth. Alterations in maternal IGF system components may influence oocyte quality or the success of early post-fertilization events and embryo implantation.//////////////////
Cellular localization
Secreted
Comment
The role of insulin-like growth factor-1 (IGF-1) and IGF binding protein-1 (IGFBP-1) in the pathogenesis of polycystic ovary syndrome. Homburg R et al. (1993) The objective of this study was to elucidate the relationship and role of insulin-like growth factor-1 (IGF-1), IGF binding protein-1 (IGFBP-1), insulin and luteinizing hormone (LH) in the pathogenesis of polycystic ovary syndrome (PCOS). In a pilot study, serum concentrations of IGF-1 were determined in women with PCOS (n = 10), hypopituitarism (n = 12) and normal controls (n = 10). In the main study, serum concentrations of IGF-1, IGFBP-1, insulin and LH in women with anovulation associated (n = 23) and not associated (n = 47) with PCOS were determined. Serum concentrations of IGF-1 were not different in women with PCOS, anovulatory non-PCOS and healthy women but were low in those with hypopituitarism. Mean serum IGFBP-1 in PCOS (33.8 +/- 21.2 micrograms/l) was decreased compared with anovulatory non-PCOS (60.0 +/- 22 micrograms/l) (P = 0.0001), and correlated negatively with insulin concentrations (r = -0.67, P = 0.0006). Patients with PCOS could be separated into those with high LH and those with high insulin levels. It was concluded that women with PCOS have normal serum IGF-1 concentrations but IGFBP-1 levels, regulated by insulin, are low. Hyperinsulinaemia and raised LH are independently capable of stimulating ovarian androgen production. Growth factors may have an important role in the pathogenesis of PCOS.//////////////////